We have studied the presence of aneuploidy, S phase and hyperdiploid fractions in bladder washings from patients with transitional carcinoma and benign cystitis. We have found apparent false aneuploid populations in bladder washings from patients with benign cystitis. We have investigated the source of this apparent aneuploid population. We have studied DNA dye saturation kinetics and examined the "NIM" or nuclear isolation method vs. the Vindelov method and have found the Vindelov to be superior. We are currently using monoclonal antibodies to focus on the urothelium and to eliminate from our analysis the reactive cells which may have different nuclear characteristics that lead to differential staining and false aneuploidy. Also, fixatives are being examined to determine the best method to preserve cells for transport to a reference laboratory or until analysis can be performed. Ethanol appears to provide superior coefficients of variation (C.V. indicates quality of analysis and sensitivity of detection of aneuploid populations) compared to methanol and paraformaldehyde. We are still investigating modifications of our ethanol fixation method to improve coefficients of variation. We are also studying the presence of aneuploidy, S phase and hyperdiploid fractions in gastrinoma tissues from 60 patients and correlating these results with clinical prognosis. We developed a method for DNA content analysis from paraffin embedded tissues for this purpose.